- ID:
- ivo://CDS.VizieR/J/A+A/586/A81
- Title:
- High-mass X-ray binaries in the SMC
- Short Name:
- J/A+A/586/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The last comprehensive catalogue of high-mass X-ray binaries in the Small Magellanic Cloud (SMC) was published about ten years ago. Since then new such systems were discovered, mainly by X-ray observations with Chandra and XMM-Newton. For the majority of the proposed HMXBs in the SMC no X-ray pulsations were discovered as yet, and unless other properties of the X-ray source and/or the optical counterpart confirm their HMXB nature, they remain only candidate HMXBs. From a literature search we collected a catalogue of 148 confirmed and candidate HMXBs in the SMC and investigated their properties to shed light on their real nature. Based on the sample of well-established HMXBs (the pulsars), we investigated which observed properties are most appropriate for a reliable classification. We defined different levels of confidence for a genuine HMXB based on spectral and temporal characteristics of the X-ray sources and colour-magnitude diagrams from the optical to the infrared of their likely counterparts. We also took the uncertainty in the X-ray position into account. We identify 27 objects that probably are misidentified because they lack an infrared excess of the proposed counterpart. They were mainly X-ray sources with a large positional uncertainty. This is supported by additional information obtained from more recent observations. Our catalogue comprises 121 relatively high-confidence HMXBs (the vast majority with Be companion stars). About half of the objects show X-ray pulsations, while for the rest no pulsations are known as yet. A comparison of the two subsamples suggests that long pulse periods in excess of a few 100s are expected for the "non-pulsars", which are most likely undetected because of aperiodic variability on similar timescales and insufficiently long X-ray observations. The highest X-ray variability together with the lowest observed minimum fluxes for short-period pulsars indicate that in addition to the eccentricity of the orbit, its inclination against the plane of the Be star circum-stellar disc plays a major role in determining the outburst behaviour. The large population of HMXBs in the SMC, in particular Be X-ray binaries, provides the largest homogeneous sample of such systems for statistical population studies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/419/2095
- Title:
- HMXBs in nearby galaxies
- Short Name:
- J/MNRAS/419/2095
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on a homogeneous set of X-ray, infrared and ultraviolet observations from Chandra, Spitzer, GALEX and 2MASS archives, we study populations of high-mass X-ray binaries (HMXBs) in a sample of 29 nearby star-forming galaxies and their relation with the star formation rate (SFR). In agreement with previous results, we find that HMXBs are a good tracer of the recent star formation activity in the host galaxy and their collective luminosity and number scale with the SFR, in particular, LX~~2.6x10^39^SFR. However, the scaling relations still bear a rather large dispersion of rms~0.4dex, which we believe is of a physical origin. We present the catalog of 1057 X-ray sources detected within the D25 ellipse for galaxies of our sample and construct the average X-ray luminosity function (XLF) of HMXBs with substantially improved statistical accuracy and better control of systematic effects than achieved in previous studies. The XLF follows a power law with slope of 1.6 in the log(LX)~35-40 luminosity range with a moderately significant evidence for a break or cut-off at LX~10^40^erg/s. As before, we did not find any features at the Eddington limit for a neutron star or a stellar mass black hole. We discuss implications of our results for the theory of binary evolution. In particular we estimate the fraction of compact objects that once upon their lifetime experienced an X-ray active phase powered by accretion from a high mass companion and obtain a rather large number, fX~0.2x(0.1Myr/{tau}x) ({tau}x is the life time of the X-ray active phase). This is about 4 orders of magnitude more frequent than in LMXBs. We also derive constrains on the mass distribution of the secondary star in HMXBs.
- ID:
- ivo://CDS.VizieR/J/ApJS/248/31
- Title:
- HST & Chandra obs. of elliptical galaxies
- Short Name:
- J/ApJS/248/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate X-ray binary (XRB) luminosity function (XLF) scaling relations for Chandra-detected populations of low-mass XRBs (LMXBs) within the footprints of 24 early-type galaxies. Our sample includes Chandra and Hubble Space Telescope observed galaxies at D<~25Mpc that have estimates of the globular cluster (GC) specific frequency (S_N_) reported in the literature. As such, we are able to directly classify X-ray-detected sources as being coincident with unrelated background/foreground objects, GCs, or sources that are within the fields of the galaxy targets. We model the GC and field LMXB population XLFs for all galaxies separately and then construct global models characterizing how the LMXB XLFs vary with galaxy stellar mass and S_N_. We find that our field LMXB XLF models require a component that scales with S_N_ and has a shape consistent with that found for the GC LMXB XLF. We take this to indicate that GCs are "seeding" the galactic field LMXB population, through the ejection of GC LMXBs and/or the diffusion of the GCs in the galactic fields themselves. However, we also find that an important LMXB XLF component is required for all galaxies that scales with stellar mass, implying that a substantial population of LMXBs are formed "in situ," which dominates the LMXB population emission for galaxies with S_N_<~2. For the first time, we provide a framework quantifying how directly associated GC LMXBs, GC-seeded LMXBs, and in situ LMXBs contribute to LMXB XLFs in the broader early-type galaxy population.
- ID:
- ivo://CDS.VizieR/J/ApJ/448/683
- Title:
- Hyades RASS observations
- Short Name:
- J/ApJ/448/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a complete X-ray survey of the Hyades cluster region using the ROSAT All-Sky Survey (RASS). Our survey covers over 900deg^2^ of the sky. Over 185 optically identified Hyades were detected down to a limiting X-ray luminosity of ~1-2x10^28^ergs/s (0.1-1.8keV); among solar-like stars, i.e., main-sequence stars of spectral type G, the RASS detection rate is ~90%. The presence of many binary systems in the cluster is a key factor influencing the X-ray luminosity function. Short-period (~ a few days or less) binaries are anomalously X-ray bright, as might be expected; however, the X-ray luminosity functions of K and possibly M binaries of all types are significantly different from their single counterparts, confirming the results of Pye et al. (1994MNRAS.266..798P) for a smaller K star sample drawn from deep ROSAT pointings. Comparison with Einstein Observatory studies of a subset of Hyades stars demonstrates a general lack of significant (> a factor of 2) long-term X-ray variability. This may be the result of the dominance of a small-scale, turbulent dynamo in the younger Hyades stars compared to the large-scale, cyclic dynamo observed in the Sun.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/43
- Title:
- IR spectroscopy of symbiotic stars. XII. V934 Her
- Short Name:
- J/ApJ/872/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The X-ray symbiotic (SyXB) V934 Her = 4U1700+24 is an M giant-neutron star (NS) binary system. Employing optical and infrared radial velocities spanning 29yr combined with the extensive velocities in the literature, we compute the spectroscopic orbit of the M giant in that system. We determine an orbital period of 4391d, or 12.0yr, the longest for any SyXB and far longer than the 404 day orbit commonly cited for this system in the literature. In addition to the 12.0yr orbital period, we find a shorter period of 420 days, similar to the one previously found. Instead of orbital motion, we attribute this much shorter period to long secondary pulsation of the M3 III SRb variable. Our new orbit supports earlier work that concluded that the orbit is seen nearly pole-on, which is why X-ray pulsations associated with the NS have not been detected. We estimate an orbital inclination of 11.3{deg}+/-0.4{deg}. Arguments are made that this low inclination supports a pulsation origin for the 420 day secondary period. We also measure the CNO and Fe peak abundances of the M giant and find it to be slightly metal-poor compared to the Sun, with no trace of the NS-forming supernova event. The basic properties of the M giant and NS are derived. We discuss the possible evolutionary paths that this system has taken to get to its current state.
- ID:
- ivo://CDS.VizieR/J/ApJ/657/409
- Title:
- K-band light curve of GRS 1915+105
- Short Name:
- J/ApJ/657/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of 7 years of K-band monitoring of the low-mass X-ray binary GRS 1915+105. Positive correlations between the infrared flux and the X-ray flux and X-ray hardness are demonstrated. Analysis of the frequency spectrum shows that the orbital period of the system is P_orb_=30.8+/-0.2days. The phase and amplitude of the orbital modulation suggests that the modulation is due to the heating of the face of the secondary star. We also report another periodic signature between 31.2 and 31.6days, most likely due to a superhump resonance. From the superhump period we then obtain a range for the mass ratio of the system, 0.05<q<0.12.
- ID:
- ivo://CDS.VizieR/J/A+A/359/227
- Title:
- Lindroos binary systems X-ray emission
- Short Name:
- J/A+A/359/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the X-ray emission from binary systems extracted from the Lindroos catalogue (Lindroos, 1986A&A...156..223L) based on the ROSAT All-Sky survey as well as ROSAT PSPC and HRI pointings. The studied sample consists of visual binary systems comprised of early-type primaries and late-type secondaries. The ages of the systems were determined by Lindroos (1985, Cat. II/127) from uvby{beta} photometry of the primaries. These ages range between 33 and 135Myr, so if the late-type secondaries are physically bound to the early-type primaries, they could be Post-T Tauri stars (PTTS). We have found strong X-ray emission from several secondaries. This fact together with their optical and IR data, make them bona fide PTTS candidates. We have also detected X-ray emission from several early-type primaries and, in particular, from most of the late-B type stars. Because their HRI hardness ratios are similar to those from resolved late-type stars, the presence of an unresolved late-type companion seems to be the cause of this emission.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A130
- Title:
- List of 1254 X-ray bursts
- Short Name:
- J/A+A/606/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- When the upper layer of an accreting neutron star experiences a thermonuclear runaway of helium and hydrogen, it exhibits an X-ray burst of a few keV with a cool-down phase of typically 1 minute. When there is a surplus of hydrogen, hydrogen fusion is expected to simmer during that same minute due to the rp process, which consists of rapid proton captures and slow {beta}-decays of proton-rich isotopes. We have analyzed the high-quality light curves of 1254 X-ray bursts, obtained with the Proportional Counter Array on the Rossi X-ray Timing Explorer between 1996 and 2012, to systematically study the cooling and rp process. This is a follow-up of a study on a selection of 37 bursts from systems that lack hydrogen and show only cooling during the bursts.We find that the bolometric light curves are well described by the combination of a power law and a one-sided Gaussian. The power-law decay index is between 1.3 and 2.1 and similar to that for the 37-bursts sample. There are individual bursters with a narrower range. The Gaussian is detected in half of all bursts, with a typical standard deviation of 50s and a fluence ranging up to 60% of the total fluence. The Gaussian appears consistent with being due to the rp process. The Gaussian fluence fraction suggests that the layer where the rp process is active is underabundant in H by a factor of at least five with respect to cosmic abundances. Ninety-four percent of all bursts from ultracompact X-ray binaries lack the Gaussian component, and the remaining 6% are marginal detections. This is consistent with a hydrogen deficiency in these binaries. We find no clear correlation between the power law and Gaussian light-curve components.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A12
- Title:
- LMC X-3 formation history
- Short Name:
- J/A+A/597/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have endeavoured to understand the formation and evolution of the black hole (BH) X-ray binary LMC X-3. We estimated the properties of the system at four evolutionary stages: 1) at the zero-age main-sequence (ZAMS), 2) immediately before the supernova (SN) explosion of the primary, 3) immediately after the SN, and 4) at the moment when Roche-lobe overflow began. We used a hybrid approach that combined detailed calculations of the stellar structure and binary evolution with approximate population synthesis models. This allowed us to estimate potential natal and the evolution of the BH spin. We incorporated as model constraints the most up-to-date observational information throughout, which include the binary orbital properties, the companion star mass, effective temperature, surface gravity and radius, and the BH mass and spin. We find at 5% and 95% confidence, respectively, that LMC X-3 began as a ZAMS system with the mass of the primary star in the range M_1,ZAMS_=22-31M_{sun}_ and a secondary star of M_2,ZAMS_=5.0-8.3M_{sun}_, in a wide (P_ZAMS_>~2.000days) and eccentric (e_ZAMS_>~0.18) orbit. Immediately before the SN, the primary had a mass of M_1,preSN_=11.1-18.0M_{sun}_, but the secondary star was largely unaffected. The orbital period decreased to $0.6-1.7days and is still eccentric 0>=e_preSN_>=0.44. We find that a symmetric SN explosion with no or small natal kicks (a few tens of km/s) imparted on the BH cannot be formally excluded, but large natal kicks in excess of >~120km/s increase the estimated formation rate by an order of magnitude. Following the SN, the system has a BH M_BH,postSN_=6.4-8.2M_{sun} and is set on an eccentric orbit. At the onset of the Roche-lobe overflow, the orbit is circular and has a period of P_RLO_=0.8-1.4days.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A33
- Title:
- LMXBs detected in nearby galaxies
- Short Name:
- J/A+A/533/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the archival data from the Chandra observations of nearby galaxies, we study different sub populations of low-mass X-ray binaries (LMXBs) - dynamically formed systems in globular clusters (GCs) and in the nucleus of M 31 and (presumably primordial) X-ray binaries in the fields of galaxies. Our aim is to produce accurate luminosity distributions of X-ray binaries in different environments, suitable for quantitative comparison with each other and with the output of population synthesis calculations. Our sample includes seven nearby galaxies (M 31, Maffei 1, Centaurus A, M 81, NGC 3379, NGC 4697, and NGC 4278) and the Milky Way, which together provide relatively uniform coverage down to the luminosity limit of 10^35^erg/s. In total we have detected 185 LMXBs associated with GCs, 35 X-ray sources in the nucleus of M 31, and 998 field sources of which ~365 are expected to be background AGN. We combine these data, taking special care to accurately account for X-ray and optical incompleteness corrections and the removal of the contamination from the cosmic X-ray background sources, to produce luminosity distributions of X-ray binaries in different environments to far greater accuracy than has been obtained previously.
